1. Field of the Invention
The present invention relates to a method and apparatus to measure filtered air pressure in a motor vehicle""s engine air intake system with a restriction gauge.
2. Description of the Prior Art
A motor vehicle""s engine combustion system depends on a sufficient quantity of air. Because cooler air is denser, engines combust cooler air more efficiently than warmer air. Therefore, vehicles, especially heavy trucks, draw outside air into the vehicle""s air intake system for engine combustion. Along with outside air, however, particulates are also drawn into the air intake system with the outside air.
Outside air enters the air intake system of a heavy duty truck, often through a port in the hood. Then outside air passes through a duct into an air cleaner. The air cleaner routes the air through a filter system that includes the air filter and any precleaners. The air filter traps particulates and keeps them from entering the engine system.
The air filter must be kept relatively clean. A dirty or clogged air filter restricts the flow of outside air and increases negative pressure, or vacuum, within the filtered air system. This decreases engine efficiency and performance.
In order to ensure a vehicle does not operate under a clogged filter condition, one can either replace the filter at regular intervals or use a restriction gauge to monitor the pressure in the air cleaner system. Replacement at preset intervals of time or mileage increases service time and produces costly downtime and over-servicing the filter. Over-servicing prematurely removes the normal build of dust particles which increases the filtering efficiency of the air filter and reduces airflow restriction. Over the life of the vehicle, over-servicing of the air filter actually allows more total particulates to pass through the filter into the engine, a detrimental effect on the service life of the engine. Over-servicing also increases the likelihood of filter damage and improper installation. A damaged filter allows dust into the engine, resulting in major engine failure.
A dirty or clogged air filter produces a high vacuum in the line between the air cleaner and the engine. At high vacuum, engine oil can be drawn past turbocharger seals resulting in increased oil consumption and exhaust emission levels. If the operating vacuum becomes high enough, the air filter may collapse and air filter particles, dust particles or oil can be drawn into the combustion chamber, particularly with turbo-charged diesel engines. This can ruin the engine in a short period of time.
Therefore, it is preferable to use a low cost device, such as a restriction or pressure gauge connected to the air cleaner system, to indicate the relative clogging levels of the filter. The gauge responds to decreases in air pressure flowing through the air cleaner system to indicate the restriction or clogging in the air filter. The gauge is connected to the filtered air intake system downstream of the filter element and prior to any engine connection. A port may be provided directly in the air cleaner housing or in the air line between the air cleaner housing and the engine. The gauge may be mounted directly to air cleaner housing, to the air line between the air cleaner housing and the engine, or remotely. When connected remotely, the gauge is usually located in the dashboard and connected to the housing by tubing.
In the prior art, restriction gauges connect to the air cleaner systems in a number of ways. Typically the gauge is attached by threaded connectors or rubber grommets.
Threaded connectors have a number of problems, however. Threaded connectors require either tapered interference threads (pipe threads) or straight threads with O-ring seals to prevent air from leaking into the system.
Threaded connectors require careful assembly. With threaded connectors, the assembly worker can easily overtighten the tapered threads. Overtightening can easily damage the system""s components. In many cases the system""s components are typically molded plastic parts, which require replacement if damaged. Overtightened components can also be difficult to detach and replace if broken or defective. Therefore to prevent overtightening, the torque must be accurately controlled. The assembly worker must align threaded connectors properly so the connectors fit together properly. Misaligned connectors can leak air which renders the restriction indicator inoperative and requires repair.
Assembling threaded attachments with O-ring seals requires the assembly operator to handle an additional loose part. Threaded connectors also require sufficient space for tools, such as wrenches, so they are difficult to use in locations with tight clearances.
Elastomeric seals, such as rubber grommets, are also used by prior art methods, often with mounting plates. Like threaded connectors, rubber grommets require careful assembly. When retained by a rubber grommet, both the seal and retention of the restriction gauge highly depends on the fit of the grommet to the housing and careful assembly. Rubber also degrades over time and exposure to the environment, which can lead to the loss of the seal and leakage of air into the system, thereby rendering the restriction indicator system inoperative. Complete failure of the grommet can allow the restriction gauge or line to separate from the air intake system and allow unfiltered air to enter the engine, resulting in major engine failure.
The gauge can also lock into place by fitting triangular shaped flanges into a triangular shaped wall. This method requires placing the fitting into a specially designed wall, then turning the device a xc2xc turn. A grommet or other elastomeric seal is between the outer wall and the housing of the gauge. This method requires the wall to be specially designed and manufactured to fit the configuration of the flanges.
Thus, one of the objects of the invention is to use an easy method to check the condition of the air cleaner system. Another object of the invention is to provide a housing and method that allows the quick, accurate and reliable installation of components for a restriction gauge. Another object is to decrease the reliance on the skill level of the assembly worker.
According to the invention there is provided an apparatus and method to monitor air filter restriction within an engine air cleaner system of a motor vehicle. The air cleaner apparatus has a housing with walls and a chamber defined by the outer wall extending circumferentially and transverse to the end wall. The housing has an intake air opening in one wall in fluid communication with the chamber. Within the chamber is an air filter having a filtering matrix surrounding a filtered air passageway. In one wall is a filtered air opening in fluid communication with the air filter. Disposed within an axial bore is a quick connect coupling. The quick connect coupling is in fluid communication with the filtered air in the conduit.
In the method of the invention, air is drawn into an air cleaner housing through an intake air opening in one wall of the housing in fluid communication with the chamber. Within the chamber, the air is filtered by an air filter disposed within the chamber. The air filter has a filtering matrix surrounding a filtered air passageway. Filtered air is then transferred into the filtered air passageway or directly into a filtered air opening located in one wall of the housing. Then the filtered air passes through a quick connect coupling disposed within an axial bore and into a restriction gauge in fluid communication with the quick connect coupling. The restriction gauge measures the pressure of the filtered air. If the measured filtered air pressure is low, the filter has a greater amount of clogging or restriction and should be serviced.
Additional effects, features and advantages will be apparent in the written description that follows.